Planar phased array antennas, for use in systems including, by way of example, communications systems and radar systems, include ground planes and radiating elements. Some designs of radiating elements protrude forward of a ground plane. Non-limiting examples of such radiating elements include stacked microstrip patches, stripline and microstrip dipoles, Vivaldi's, Helices and Monopoles. In mobile or transportable planar array antennas, radiating elements may be arranged in tiles that may be connected by hinges, to permit folding for transport. Referring to FIG. 1, a partially cutaway view of an exemplary prior art planar array 100 is shown. Array 100 has two sections 104, 106, hingedly attached to one another at hinge 108. In section 104, radome 110 is shown partially cut away. Radome 110 is supported on standoffs (not shown) above tile 120 having radiating elements 122. Elements 122 shown in FIG. 1 are parasitically excited patch antennas, having radiating elements 124 on dielectric supports 126. Elements 122 are on ground plane 130. Radome 110 is also supported on ground plane 130. Radome 110 may be, by way of example, a single-piece A-sandwich, which is a layer of foam having layers of rigid dielectric material on both sides of the foam.
The A-sandwich radome 110 is both heavy and thick, adding volume and weight to the array. The standoffs 112, 114, further add weight to the array. In order to obtain access from the front to any tile 120, the entire radome 110 must be removed. The removal involves the use of personnel or equipment sufficient to handle the relatively large and heavy radome, and exposes numerous tiles to the environment. An alternative prior art radar array shown in FIG. 2 is a folding radar array 150 with a multi-section radome 160. Multi-section radome 160 is made up of individual sections 162, which may correspond to individual subarray tiles. The regular periodic discontinuities between sections 162 may result in grating lobes, which can degrade the radiation pattern performance of the array compared to the pattern performance in the absence of a radome.
A-sandwich radomes of panels of random size, shape and orientation are also known in the prior art. The use of random sizes tends to avoid periodic discontinuities, thereby reducing grating lobes. However, such panels are generally large, heavy and difficult to remove. In addition, the differing sizes and shapes of panels means that numerous sizes and shapes must be made available to replace damaged panels.